Drug-related overdose deaths are now the largest cause of injury death in the United States, having eclipsed motor vehicle-related deaths in 2008. A number of interventions have emerged in the last decade in response to this epidemic, including prescription drug monitoring programs; improving linkages to drug treatment; training drug users and those around them to recognize and respond appropriately to overdose; and, most recently, training and equipping law enforcement officers to use naloxone (an opioid antagonist) at the scene of an overdose. Equipping law enforcement officers with naloxone is intended to capitalize on the fact that officers often arrive at an overdose scene before other emergency services, particularly in rural areas, and until now have not been well equipped to deal with overdose events. In the last 5 years, with the active encouragement of the White House Office of National Drug Control Policy and the Department of Justice, law enforcement agencies in at least 28 states are planning to or have begun carrying naloxone to use when they attend overdoses. Despite the proliferation of such programs, this intervention is completely unstudied. In 2014 the San Diego Sheriff's Department began training patrol officers to use naloxone to respond to overdose prior to arrival of other emergency services, and to actively refer overdose victims to a collaborating drug treatment agency after revival. Uptake of drug treatment has been higher than expected (3 of 9 revivals in the 6 month pilot phase of the project entered treatment). We hypothesize that the moments after an overdose represent a teachable moment in which drug users may be more motivated to enter treatment. In addition, we hypothesize that having law enforcement officers respond to overdose as a medical emergency rather than as a crime scene may make drug users more willing to call 911 when someone overdoses. The overarching goal of this study is to determine the impact of law enforcement use of naloxone to respond to drug overdoses on two primary outcomes: (1) uptake of drug treatment referrals by overdose victims referred by law enforcement officers, and (2) rates of calling 911 to summon emergency medical services by drug users who witness overdoses. We will achieve these aims through a mixed methods study that includes secondary analysis of data available through our partnership with SDSD, their drug treatment partners the McAlister Institute, and the County of San Diego, including 911 dispatch data, SDSD case records, and treatment data. To complement these data we will conduct qualitative interviews with a community-recruited sample of drug users, to assess their perspectives around treatment referrals provided by SDSD Deputies, and their willingness to call 911 in the event of witnessed overdoses. Interviews and analysis will utilize methods drawn from grounded theory and ethnographic decision tree modeling (a rigorous qualitative method used to describe how individuals and organizations make decisions in given situations).